SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '561ef870b5cad280db7b64f1cf3e23fbe080f996b3e161c2bc264c7a0104cfb6' 
  AND token = 'p/hwA5jGMLutqU5w5tAM1RA30vzMY/OG145CcXLNS3o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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