SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '504510051ed6c4f3399fbff841564fddcd9802185a5208ebaa0717bb72da4292' 
  AND token = 'OA3BtvfmXQPZ+4fN86Lc9BKkh52qB3R/kACFMaFpmLU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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