SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3dc400b5f29b974518d20327e4bd531bb51fc68eb6e8cf0c787668f46b6d449c' 
  AND token = 'h1v0v3oVqDzvL1z5bvOKOjhZOd6ysP39n3Mkx+qWNQw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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