SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd7ebad124290def703c81a11817d3763043cb8984a21979f04874ba97958354f' 
  AND token = 'riFt1TAA5QL+hTnZa7OKbfKuMCr2VILaPC5LeQ4CA78=' 
  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"
    }
  }
}