SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35779237e4ee251eb6f979d7ae153313a0461ac9fb8963d79ce8afd6b7013d56' 
  AND token = 'DTGEJ++NcJ1HgpsZHrKIctA3hbUHIfAB+h8cDVvEPQY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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