SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '66ac61b2655967afc5a1941ef52d3e7fa79da1a5f7c1aeef44e604e09e06ae03' 
  AND token = 'KY7BmHq5IgJ9yzwuvK5gTDlN66Xo2v9KCz6fnkoHYKI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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