SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2d5854693dbc67f603f038cfa37951741fc968241471d34e8935814625a54ce2' 
  AND token = '5qx+zGyDz7K6QXJzg9/qihVkeUvBqlRAMCUyJZFB6k4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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