SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '49a4150f71cd5f7d8daf221527f18a9cc5a691268426266ed37139c35d180675' 
  AND token = 'ZGBvp1uAquFNIrJ+3fRZ6xVmnhgVlcKNulcqi3NQwr0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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