SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc4cda5dacbdb33deae18f01d2296898af0eda94ff5e3b8e76d7b082139167df' 
  AND token = 'nfmMQPJ6uqAp624+5qKUAlMIVwwSAOE8uZuf/id5SNg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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