SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6a15a17d711a02c5e57dae0bc58d84f1f227702f1a1a9faaa24d6e8d5945648b' 
  AND token = 'HHtr/vMbO0QKcqK+EmJn/ZnspAhZrtzFwkF6CXL2CFo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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