SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cbde08bd18b8a8ea68d99a05808fa8273972ed420c0e8e534f4f5b830dab9496' 
  AND token = 'n+V3+PjzKMpbPePI5Jxk6nLQvC6YgkKDCHolM3BZoCU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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