SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'acac4addf92542f74edc0dd0f7718f240963f480b342f98cce82b885a5f28bfd' 
  AND token = 'SzoGhC+8+ObsS5D/4Tg/5vLJdbeqVhKmawMItXll6AA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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