SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b3ce738744dcd56bdda84fc25054e3923464961a29b0285c9ab4a719fa0829d' 
  AND token = 'IXfzfN/Jc6QTFN+JqVkZFLU+RcdnCxL9G1hFDI5H0hY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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