SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2fb7998211eb22112227cba97931029d8b4b3f53369344d29e0c5ff0f516da85' 
  AND token = 'sSS14pKVh75qTrk1t45Hkp9Mp5d18BrExiBL1IbyVpc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}