SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42101813569bbeb3cde2dccdcd39d341b75e2323de81ca209fff6ed3a138eec6' 
  AND token = 'oid52M76c8pBPzA++pMe7QiphhGQshzOrM1GtaONAtY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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