SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9e59582094284cce3b8eb49b51840e0da4e365287115380903428eb25d31380' 
  AND token = 'VNl7zImn2KuMTUkdoY4jPgOCfW0UH5pbfRgWIPW0iY0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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