SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc3d7a3f422dd31589bbbc12005fbff1db456a7cdbc9d519567bd7c944c68727' 
  AND token = 'H/RwLP6VIok8ioeHIgrpiy4TFzUazmSZWClhyCWk+Vk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}