SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3943987104dee95181ed592ce8630e78dad3df4c862603ac206371473b517aa7' 
  AND token = 'FHaRCvejsYaNnr9b9KfwqzNOQt/k+QWuC7gx5nAzA/c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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