SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ea689be23fb3b72066072c0ace0cea47ea6712fccfc230a7f661b9fee4f46991' 
  AND token = 'y/FoRSqWS2ui01bGioXNyBCpFER50JjOZwlzFZi/X2U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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