SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ae992fc39b912b1274e3357e614c58f2ba12c678dc194af7c50e1f0743cab356' 
  AND token = 'IoanOZ2MUxSWpBcHrtAXI4xaFTslwh/aaaSzUByaHOs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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