SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '083cb7f469f455d5e4011523aa999e37756efcf21941e0461789f18f581b64c1' 
  AND token = '+dMfXRwdbYqMVWWK+TXJOPXZvFcFy//bh7AWXVLz9xM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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