SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2ebddb07d62dc73ee35049eca8bdbb4f0d261894cf2126d684a832b765a43e5b' 
  AND token = 'DzPIJ9rzWVBEs/WkFYawnv74UmQoIjaZrsPpFVXoJ68=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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