SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '03435af557195a56e9fca4d921cd84290d4686911fcf5e356a5408c25b074057' 
  AND token = 'QakKprtM38jAiUOyaVTchQG8m9ZihdW7crr6h91IkvE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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