SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a8adcfb10ecfe01b6efc1513483c500c091a7c2a9455c6881001417cd06c95e' 
  AND token = 'CRDE8c+1XbnIT6Ic9xUzLOXB7etF0TcAbgMerienCXE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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