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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd9de3bda03f8f9e6b0897c3fc66e4077b257937b3fe8fdf82a1d03a77537cc42' 
  AND token = 'fme3Fhrhu+DqVeEYkhaa1DSoZ43TN9DdtHnjIolCy0s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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