SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '243bcb6811688e0c72e5e0735b9161dcee1115873c8073ad939063df18d241dc' 
  AND token = 'kG8avIP2qao+g+KSzPZDAgGznILjXZlDKPIzjhu8jcE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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