SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f68e2e875a2a72830415f13c126bff13ebd419fbc02e95c3a20682eb032793d' 
  AND token = 'JYo0heOwr1RC1TJ2skIoAHU42duqAKr6HnlwNbXlAHs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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