SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8b5cca5934655936c7493254fa96314085cbd780dc290253839739a0a6e93be' 
  AND token = 'e966UREeQZ88mtUWTfelo1YP7o6Osz5VAL0IRvsenAE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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