SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4cf1120d466928384b50163dd4c0d59d0670cc86dcad788b93125847c263017c' 
  AND token = 'fEoI96YyzaDqP17dTUMcyc6v27dA3UwiBGDgFee4LWw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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