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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7f078ff1df3ceb193e6f6dd8b30c9f239e8b845615fafd3794ee6fb0eea3d76' 
  AND token = 'NRFFGphAgtwZYzqz9qYx/6M0UuF0xJY673bKOxdQ0/A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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