SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71cd00b34f3ead66dcee544aa53e43befdc2f468b82ec8039357d93994ccc28d' 
  AND token = 'De9i8nerKLs0egq0sEiOsPG3jiDzS1ftsTT45OaP8Ek=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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