SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ec9f4cb5963bcaeef1a43091d3fbab2fc7fe5ca25ad6d3aa039f79ffeb50cec' 
  AND token = 'ihAD3PPtEnfqcDzQTIDoNJl+jSVk1rvvJA5GcKkFw2Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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