SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42e7d0c3be670b7320c55b90b6e8cf2940fb953df2318b8a9bdff861bff09727' 
  AND token = 'uYlsnxAyn5RPS/0n9yeHiwj8R2rkwWxlRQZc4DbJrFg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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