SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8dedf4f1b27904d29acf7f5db65266626f46e65563e4e7d902babc53f1c13c20' 
  AND token = 'LRxwVm3v8oAMsihJ7hOC+MTsJW8HfdQmOiMsEqMPRm4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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