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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8151b3bd2ec533e2d50420f484fc3096991029716e876851fea2884a9a1ab65d' 
  AND token = 'Omad98DMbzt3hy46Fyv9eRzALe6EcDHUdf4aiyzMndI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}