SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0ecf3ceee56142fba34d56065e84d096a59c3e509d45960209db679f2acf6eea' 
  AND token = 'nBeYeV/9B50jsdNsjbqwCOkj5jynffqwBRDygwsO4Zg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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