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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6fc5bdf5327c62a7a016ec900819a05d78b5e99b4a4e784a6a5f63ee1b8abcd2' 
  AND token = 'rnAhPp3Uhv4aZRtvlnULvw+E+eI2WU+OC6WptnNlTCM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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