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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '300ba0bb70a4dcdb44299e2cd32f7282c294e117d13af1bec1b915081e6962ad' 
  AND token = 'iVhSj9qzu0+Jjtu8Pw1li8eOkBBXqPkFHpW1iYp6A9w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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