SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c365b283649aa30dd2bdd8feea927bcb4c69a106f8f6385074a8fd90815b9cf' 
  AND token = 'k7zWE/RIreszZd05GwqJiF0JxgMbnUfWp3Res0Ktj2w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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