SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ea895d325c785e99356fb4a32cbed459793e3daaa59f0e0125b1e3e880e6d352' 
  AND token = 'Nn8zPMcdLWgX2GwOTM6KbUmTVp4xw6yILgolaMrt0YI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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