SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7517203410bc3315fb0b623ba83250b20801a6355d75565767121edba276461f' 
  AND token = 'Zm+Kv6nDwi8RV3ReLxrha00QrCwAzEvg6c2FliFX3rk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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