SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90584560db9c121721f4981377dcb8072bf4b640daf977a2c3599f78411663d3' 
  AND token = '7GVbXZ5N0ahzukOjpyrJmlviz5ZjwCe+cF3osrQQbb4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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