SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7646af7477811be0808f560881c2e7ef77dfced11ee873b9ec455f6f54b2ab49' 
  AND token = 'N9rL+923vacASLWvm3PJldYLOyhe3tOz2y02GL7PnGM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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