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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8e2d8e15fd598d5e76d15ec5ffe4b2737eb0cf468f09a3820f30619b3b9e221' 
  AND token = 'QRpmxvTSzVadilsUmXjZrTcoOu2iFd2sUXHQ7pL/DcM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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