SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2f67d2d5dec894e546487536ccaaf4bbf31f3f3da9af4f0362f0acc24a03d7e9' 
  AND token = 'cihkOzp1wcDxrKeP1uwVAfImjaCHppLYjJZnnGlg2Os=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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