SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1fdd6c79e6a762565830fb6e749d9ed20047fd09ccb731e68c1c4b1f13f1832a' 
  AND token = 'JusYKiC+bkR2GaTbBPLkMeyqP+r2dGsUuPGlvRGmH/k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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