SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50f96a9b25b5bfb8b5507526395f204f7018c730d8efd13640d94db928836494' 
  AND token = 'ffUojhy6FyfZaLuiJ0+O401l9UEQB3A2W2jlcMyRC8I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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