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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3ea68ad2af2520d886df6591de0c4f054c0efc1ea64f1fb2c1675e6327166f1' 
  AND token = 'z6+WX2q3GS3T2ro1ttwP8mFf+k9lXFfsRAY0n0KMUTQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}