SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd588a0c982e4cb0f5ba3ff09df346b4b96a2dc2d2256d9e41268fb9b14c96b46' 
  AND token = 'FUfP3LWTz+Z8uLYdjvuBonOxCr8Bidbfu+9REPiTENk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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