SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1852f6d0cb362545518543d93e16d25f1a714e3d1ea4493a9f0346ca966711c2' 
  AND token = '+JTs/keDcvAHwHSl9IgrCjwEcDJOKnOq79vIjoJhtRc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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