SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b42e22a4725589eb0427f18a3a05e39ab210feb330aec8d27597948db6e69f3' 
  AND token = '1CO9X0xRqvin2P+mpCxC5NWYAFvOl+BKBpLO+Q6JYt8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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