SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a68bdb425d150ce857c02a468714e9ab4f3f299f56998f2f01e8739d19959805' 
  AND token = 'P37VngAMzCgQSli7HqCbpXfoFcliShHw5/hWfxueLzE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}