SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39db36d0077aff0da938e66714edd2059bfe6ed5fb04bb1361ec219d81de9a76' 
  AND token = 'E20E8ZcTkoRI0OvRB4Cl+tcFDouNsTXVXXx8urLJZb0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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