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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8e6689b9283ce145c2adbee908dc8d6a81be70cfcc1107c6761537d9b8f568a' 
  AND token = 'QDZBna2pOzDTfMaCakpLyFS9JH45dy+kGVGey0rxfl4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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