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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '297dcd94d6acd6dcc05e39fd442269070f8295c51a2fe7942dba59c1e8c58c08' 
  AND token = '1cOSe5O/nYlqaTyXYGFoWPj2TCqwlTFDS1nXw7A6x/k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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