SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '796acff53698b88c76d5ef65e619bff3ab713ce8fd9a4b841d41f65e9bad0464' 
  AND token = 'q0tcr/yFY9JKwZ2+p5rsjX9yYnXpQnzcVYy4SdJdB8Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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