SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40f1ca5f86724e28684394c77384193883051e30537a9e5c160414eaa4ce32f3' 
  AND token = 'Tz4OR+S+NtenAnYaAQ961j4FSSD+3bVsd38caDKcmXc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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