SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d23a931cab8121e98e5bfc5eb0ed9d3878e2bcf633bf109292afce826f07009' 
  AND token = 'bo0VjqjjANnAVoGCd4+KgbMYoweue5uQbs61N5g86Ec=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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