SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '23c40a5312514b623afa584b6ff7adc71c492f7e7d35aa80b94f666c6dd40d36' 
  AND token = 'YXK1uVd+tlrupDxvuixMTFZl/qMFuxim+lSfJ1gGkuE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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