SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ef73a9510f901e40394139bceade071e21f36a5c1f232116809da09ca6d7a4e' 
  AND token = 'HAdjGBcaPGM7tKHDdTzG3v72/aiM9UdfZ4nCHjP503s=' 
  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"
    }
  }
}