SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eac88ec8ecb1b3d04d304323167056dc4078b9f4e2f8617a0d26600a535957f7' 
  AND token = 'shVTAtAd6SSZGqLA2jPRFrjKU0qHumjWKeLvc8JujsQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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