SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3ba2141c0ca813907bca1d93786caccba1bee99606e32f28c6d49b2d8a4ff20' 
  AND token = '6JiyPpimMzl3hG1jIpWdZEUmKXb3OelO5yFe+g3vKJ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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