SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5b9adffed64558921226180172f5004429f1d802a618a2aae3257956c9ab948' 
  AND token = 'k6bQunZ0oY5CyXJvn/IUY2g4FBsSDGY26qCj6HRp++M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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