SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bb6a255aba2b73878f32a25c265dd04777d5322378ebf3461bc4d64f173a88c2' 
  AND token = 'eLxX5D++MCvGUM+gO536NxxIJR5uEgM/uxvQXeht6nE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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