SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8fcd773ea5a28d63d2d4abfaab474ec7b608519634205383f553725b8594264' 
  AND token = 'JqJeh0V3l3+3rYlcQZnwUVG82CLQFn6r92aRH9j41jw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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