SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c04dd92db681ea7f5635d2aea258e2bb436b746637edd75ee32fdaa58f4ce00' 
  AND token = '2RAZ2nhPnz0VL6+jekffNSMv+I8kR5dtrcFuFXbUQfQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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