SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '537b5ed9137e9f47edba329ce5f9a82bacc2b8fb90d226253de0fc0521b794f8' 
  AND token = 'rpMMEtNp0IMhTboMdVWDaNymuFo9n12QDWEeSaN+CzY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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