SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c2c3be6d7ab37343ad52a99bccde55780e44fc608df0383126c325a6aebb1a3' 
  AND token = 'keQgmMYImKhutTE7nxOvjQSWDK8NSi9gNjLRbUulrzc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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