SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff73125943ae88c17fe4c823b5d1cccb87c9945fc0835dd8ef8ca965988c5081' 
  AND token = 'gDkRkyZWawIM+HZq+kYjw1aZpqDEsJj/ZvyItlpPjoA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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