SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6daf9801a7998275642d02bb0a34f637d99f6aa0cf5ccd13b091cb21f03e6bc' 
  AND token = 'z3IxCcMErYeGFlbRlRQigHjA1DjuaG6s2WyHdVqsBSw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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