SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e9947e9fa866792acfd53d0a5a957c5dc1f6985160b425ab0bbf7df1a3cb3695' 
  AND token = 'MM5PAd6TFZH09D4tTx2UXOiCsOn4S+h3MA25b3Nc1M4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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