SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '691c726073db710e1b372aab75dc8be73c4c2853c2fec0fce99113af2554ebcc' 
  AND token = 'En3PvY9qkBk7Q8FsorjHAJqWDf8MpA/VGUC2MwOwzIk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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