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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c1f0987abe3d470a844287de0a00652d11e54ef58566a8fb7eeb4223b521816' 
  AND token = '4+TbMdc8GmkNB8sE1bK5XseRkfN51ZhA7jEgUYoPwqg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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