SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42bfcec22135bad75a8bbbd80e32d197f72a3dc11504c95a23e9363765673ccb' 
  AND token = 'tfaJIQW6AUJj27qnqPvjGn/jH/1/ssTnFUE0nwbSzYQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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