SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b02e3647db6b2e351e979e4816720bcf3a6fc7b239d15376dcc5560203880bab' 
  AND token = 'NSugU2GtnvD117BlWpRk6JVc4jfj0RpTjf9di8E094o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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