SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd51ffb683e0dbdc279ab05bd3ff1d407a77cffb540f4cde8b3138b147f396ae0' 
  AND token = 'XqMNavG7Uur7i8OMuXpdTI5fzaMe5URhPLjJu/iULQg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00061

JSON explain

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