SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ff5034ebe2a4b434337c3633574c19437527811a3a0905b39961b8d34fd3b77' 
  AND token = 'F0HfKGG+zScbdEcyNbamuQXhwPxdfAegcnS6J7DdmGs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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