SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b17ba25497fc13ade5df4d52f023bd2bdad9b713ca6c62fb5fcb2938a960564' 
  AND token = 'UzDTPfx4waSixgKzwMM2zKt2jlwzzlMnMYPIH0gEOUY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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