SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f3e854d612bc5cda06f1a2330e5ae8dfe939957e3cc4beacc7bccf5de63746c9' 
  AND token = 'aKnzRenYbuEjDqJHpMwam+b3JQ/VXSuhdmQTUTBsJoQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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