SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b47e3dcbcbeb0a59dbe85e100aafe249b7a874efc9377c502b5de8c2e7eab76f' 
  AND token = 'jcFMx06lp1kdGUWnvq0RZK5ftJ12szO+aq/FrFNQNz8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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