SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8108e47ba99bf46d6d0d3c135d86e43857573dcc0f73e2d51854a0dba9888cd' 
  AND token = 'PgJhcKXzdrVqckQLHCjplVuethD+ZS2nTHIOWNO9xbs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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