SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f49cbede5ad2f03a709666a806bdb12878b06cc31b43c722c0299403a47967a' 
  AND token = 'NRH5Or6TfCHs32XgK1kexFZzu6sUXAp/GnJ4iww+uGs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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