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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83aa1708227d739fe62d7fe0f80f6e388f75c84b21f50f3872152c7804fe7c82' 
  AND token = '6WD3zafkKwA+9ZXfAVBAg1x7x3CvhQE8qGWZjkiFBXs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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