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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cfe4067a4320ba0ca6c7fd7fe3eac0c21e4b6baf3d59a61441b26a1829c54913' 
  AND token = 'F8Vwkuq+CWiP0raPMz7dpUXFbOR+D/m6llQAnBsZbmE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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