SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52cdce378ac76c8148a832584ddee15381ecbb3c1dbb1b114a4a08b745daeabc' 
  AND token = 'Q8xA7LoijEBGwlfjGe3TZxlgYpr6bfd8Zmleokz/soM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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