SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '57707f6b88adb2978d58b589082a3477a99cb4e0082e3c75401e4058f3ea3546' 
  AND token = 'AV1VT2JMQYW0IN005FYFrXvCIUQAVbqImaKosmMDJB0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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