SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '736666660bfbeee5a2646ce79c8948a8b55d43ede964b6a6bbba0ef7d65ac971' 
  AND token = 'NzgTCcpbdbuZksIaObbB3rtV3cNBlnDXJjiis3kcz68=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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