SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e928c0893cccdf23d099930f6478cfa2b5f9d08d236cabbb508c1e688116b2e' 
  AND token = 'VxBdyrhG0PSwysDKvJKpCXBQkOaZynnpCDmPPidsRek=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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