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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b78b9a209d8f792f7d9005c5c8c6ac77e4ddb4887ed9518c760bf7ca6796872a' 
  AND token = 'KUAjRJJPbACB312QTij853zxZYHlbi8SjFhtsuwwWhc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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