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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a21198e281263f44f92e6947e0e4f461c65eeb2bdc039a25877cfaddd831a0f' 
  AND token = 'nRIiD56oQ+znAGCA87toPGcBSM+jaqR9pSZGzzhJcm0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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