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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4d274764e1bb8884abf44bd2e63c2f13cefa1611cc5b16e7572bd850a42a347' 
  AND token = 'yfamt06X7SPzvhJ/OpR1NdRYfRDx1mQYRLSNRxzWL/g=' 
  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"
    }
  }
}