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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c7f6faeb924f1393cc41448d069482b88f8c1df355f70dcb64c91e96da63489f' 
  AND token = 'Uz0VHdTvKncOpcCEXtBoIOAd0rauY9+tS832kv97Xug=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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