SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a65795a38acb961770af05c4e38e6ee9679022a05eebc2773383231770708e5' 
  AND token = 'qRRdQcdd1zi9kgdBazENINE6PPuc5VZNy40aCuBpdgo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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