SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b91086d463d19c4cc5fcb608a7fd6693f8853aba21ffa90d081a02b48f8e764f' 
  AND token = 'gW8qrmbN7JGzN59srrhbXyXogeLTB7tgc47Z8EPIxnQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

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