SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b791b991709924fedb948d8ff6760094127cbeef1f67495c04a85a4b46e6a2a9' 
  AND token = 'Nc4T4dQ6xeijMlfcuykFzQmQiA/zY2Iaa4jSyHHshmo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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