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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f66cb482cbb29997e63387d9c0c4912d6c9fc702e5ba7784fdb0fbff8eaa8f70' 
  AND token = 'BMTQTBoEhvnTO31bE1mxqUXgUfhXh1qOyBu8HetvIQY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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