SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df8876d12f57a6c57a291767000128662c23eecf337fdbbd1f8122f2f8f65812' 
  AND token = '1BRmYRcaXXP8peUKvtEqOQU9CCb+SDoe3AZrjQpU5lA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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