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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6cd1cc368d78bc35ebe15b98732105386cd77291a7aa58a2aeb8c2f730a6ba9b' 
  AND token = '1/6P7DFb3BOTLWv+jxLNzoWGusCqrzRZfCMsIRy2QJo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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