SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91da59b75a23e07231d4ca8d49a798bf1425058de97305454d41fe8263cd9350' 
  AND token = 'C3bLGWt/0kVNiTh2GqwTTDQtxexQzJKSYXvdsqUbitw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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