SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39801a57da6a9d38455dbaa6303365340f03887ffab64f207b6716251cc92b79' 
  AND token = 'sAH2MHP/HMvzCkqZmHi7hSCFMKxNoDkpP5qWpDuqmgM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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