SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1d962286e49385806ae72887476d5392cd6c794aa5ec97a784d6f6c994cb4895' 
  AND token = 'A/McyCnnM69dXGS1tYUfk+2PVsOvIfrgwAFXhuGaaCM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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