SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cd1dc4ad8084c88228a949f26dae5c1e1775c5f8143acf7b4103c0394e4f194f' 
  AND token = 'x+Kq/MvaJ6AXIIeGkkuth9U8xuPFKNWWJXznkTUR/ZI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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