SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '06eb38d15049053a9226657c037aacde7fcfb6bdff7503c782077487a9c7b992' 
  AND token = 'dgkzClRoxpbSLbzO3dua8yRAv+oKw1GoUK6KE84miTM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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