SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2c1fcd0aa1fd370286d42ea622acc1ea0d6fc591a6d5114f7ea6137950e4831b' 
  AND token = 'hlDw6Sid5t0mtf/pwmHVFLB6lDNTPtc+DUh8SpFQkK4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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