SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd16351e5fda12db8963ca3e6271b709ec485985325a132978f22caffcb81810c' 
  AND token = 'OZEDd6QqRAgzWbXEiNKib6tvYCRfnS8yIeBlNfyGNfY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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