SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c88f06049b84a2a9b74a29c4fe6882625f848163de15cdbec23738f519b67cb5' 
  AND token = 'RCI+8fMQj7SwCQ2IBFPd9ZoZHS/lQCydRdknPEKCz3g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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