SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '685191156a1cd182cb9f5a2ff4639bf1715a3e1441a4dccfc38a33df368b3627' 
  AND token = 'ncN4cqCABH3vf8nM5Ug8kzgB6HTMSVuJF+mGCcKnGVI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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