SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6f71934f279ce87e6dd60a53802bc8129a194683bf6c6dbf58a78cd24eb2a5f1' 
  AND token = 'OCrsXZLuzBv9w/YwZitKlDD498XRfIlIfNp0d0xQScw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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