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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f63312fb24e5ecfc5a32d1fd69beae5e2c17ad82a18d33d0aa829a4c7333d2b0' 
  AND token = 'ksUfXP18qcnQYJQlk0QcFw9rrUCmgVKla3+Pn8mIalI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}