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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a0df401b0d3675352629891aa9fb6fe6e0f90740f711fbad88ea6925c4e2cb38' 
  AND token = '8wj5abVDx+tj97fyBnxdB93yOxuvAXy6BfNo/GUXiSA=' 
  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"
    }
  }
}