SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29b1888be610e87feec2080045c86712e5485787f5f781d2f8b10a2f57b42d9f' 
  AND token = 'jJ/ikXojtjym1KLD70Y6s94paV6gEDxXL400OUTqfII=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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