SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '521ef5cbacbb08b231b4093ff291d42de0a72b89c015afeaf597a9ea119b8369' 
  AND token = 'wXQdmMmNkLQh73GEqyrldzVrLNlx3pCKpW9/IBtE5bA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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