SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a393be8ae316185688731c956d97ca44f107b3e0c8576d7186684b024e52f377' 
  AND token = '9HnLF2QPrcZ1U4NHa1HvJLHelJhnG+QlfuvrjPowVqU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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