SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cbf783501ede1e87eecb555e786644226d0c8dcc9c33c5d96b71d8f62727a6d5' 
  AND token = 'zf8QYtFzqjHK+dSdSAYo9GmUKwJUlMJB43BXwOn5FFc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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