SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '524840770349e454afaf369af6fb5fbf1fec9748ef31a25e7584798d10f099a1' 
  AND token = 'nI/07SfighvQYjPuTl1Q6GX91VqdXujMskCRbhE+jsw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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