SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6acc15bceef332383c0796925d8496ca108426347f97304c3538d151199f296a' 
  AND token = 'zd6PugB+6ajlgOT70wHFZRmgbkjoj75/3vJ7qEsXn0U=' 
  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"
    }
  }
}