SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b471420c8ceb656f29b49354ac521f516215259614d4fcaad75be9af9e0240a9' 
  AND token = 'xhSmcGMI3qWCDm+1slD8JR66TeCRAFzZpZKZrkqPl+w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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