SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '49cb493f30be6a10bc92fd58c8e67dc7c077821fbd9c3552c8da1f4a62241af2' 
  AND token = 'n7WhYWYVbASBaJHmkwmr5HNqBd6QDNkzxPTt1q71YNY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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