SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f1b78f961eb75b1a19779f8ea86e3aefed43e736ae912693da458e7a12b2217' 
  AND token = 'YKzl3yUDaDxp5Wd+FBjmyRI6arsEgPghSvZ1w/dZPpI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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