SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c65111565b990d2a23246dc5beb1a98e5a41396c79d0f1374048d5edb6a3da83' 
  AND token = 'wG5UOJViPMs8LgMpjjAdwcKob+tVVDghxkmh78ReUFM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00062

JSON explain

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