SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '47e83fea4373ab904d968f5808a2b6bffb5e88249d691d7eea8c1a368fe7590e' 
  AND token = 'S0xWg5aGnCXIUYZKLhHUhBNBPKxXqPLkWWZWJAXM9t8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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